Heat curable composite textile

ABSTRACT

A heat curable, circular knitted fabric includes reinforcing and meltable resin fibers that can be cured to form a more rigid material form. In one embodiment, the fabric includes a core spun yarn, wherein the core may be made from glass, carbon, basalt, aramid or metal. The wrap surrounding the core may include resin type fibers such as Poly(p-phenylene sulfide) PPS, Polyetherimide (PEI), Polyether ether ketone (PEEK), Polysulfone (PES), Polyphthalamide (PPA), nylon, polyester, or polypropylene.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/629,773 entitled “Heat Curable Composite Textile”, filed on Sep. 28,2012, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to heat curable compositetextile fabrics that may be cured to form a more rigid, non-flammable,heat resistant and insulating fabric. More specifically, the presentinvention includes a heat curable, circular or warp knitted fabriccontaining reinforcing and meltable resin fibers that can be cured toproduce a more rigid material form. This composite textile may be usedin any application that requires a rigid, heat resistant, non-flammableinsulation or sleeve positioned around machine components having aspecific shape. Application examples include exhaust insulation covers,pipe insulation covers, machinery covers (such as covers for turbines),rigid fire barrier panels, gun barrel covers, engine component covers,and the like.

Traditional composite structures are typically woven or axial fabricwith longitudinal fibers to maximize composite strength and rigidity,but typically require a liquid resin and some form of molding, usuallycompression molding or vacuum molding, which are time consuming andexpensive manufacturing processes that require complex equipment.

Compression molding is a forming process in which a plastic material isplaced directly into a heated metal mold, then is softened by the heat,and forced to conform to the shape of the mold as the mold closes. Thecompression molding starts, with an allotted amount of plastic orgelatin placed over or inserted into a mold. Afterward the material isheated to a pliable state in and by the mold. Shortly there after thehydraulic press compresses the pliable plastic against the mold,resulting in a perfectly molded piece, retaining the shape of the insidesurface of the mold. After the hydraulic press releases, an ejector pinin the bottom of the mold quickly ejects the finish piece out of themold and then the process is finished. Compression molding is ahigh-volume, high-pressure method suitable for molding complex,high-strength fiberglass reinforcements. Advanced compositethermoplastics can also be compression molded with unidirectional tapes,woven fabrics, randomly oriented fiber mat or chopped strand. Theadvantage of compression molding is its ability to mold large, fairlyintricate parts. However, compression molding often provides poorproduct consistency and difficulty in controlling flashing, and it isnot suitable for some types of parts. Fewer fiber lines are produced anda smaller amount of fiber-length degradation is noticeable when comparedto injection molding. Compression-molding is also suitable forultra-large basic shape production in sizes beyond the capacity ofextrusion techniques. Materials that are typically manufactured throughcompression molding include: Polyester fiberglass resin systems(SMC/BMC), Torlon, Vespel, Poly(p-phenylene sulfide) (PPS), and manygrades of PEEK.

Vacuum molding or forming is a simplified version of thermoforming,whereby a sheet of plastic is heated to a forming temperature, stretchedonto or into a single-surface mold, and held against the mold byapplying a vacuum between the mold surface and the sheet. The vacuumforming process can be used to make most product packaging, speakercasings, and even car dashboards. Vacuum forming is usually, but notalways, restricted to forming plastic parts that are rather shallow indepth. A thin sheet is formed into rigid cavities for unit doses ofpharmaceuticals and for loose objects that are carded or presented aspoint-of-purchase items. Thick sheet is formed into permanent objectssuch as turnpike signs and protective covers. Relatively deep parts canbe formed if the form-able sheet is mechanically or pneumaticallystretched prior to bringing it in contact with the mold surface andbefore vacuum is applied. Suitable materials for use in vacuum formingare conventionally thermoplastics. The most common and easiest to usethermoplastic is High Impact Polystyrene Sheeting (HIPS). This is moldedaround a wood, structural foam or cast/machined aluminum mold and canform to almost any shape.

Each of these methods has disadvantages, including expensive equipmentand time-consuming processes. Thus, there is a need for a compositetextile material that may be cured and formed into any desired shape,wherein the final material becomes more rigid, tough, and is resistantto heat. Further, there is a need for a more cost-effective, lesstime-consuming process for manufacturing such a product. It would bedesirable to provide a product and method for applying a protectivecover or wrap to mechanical components of various shapes and sizes,without having to produce individual molds for each specific cover.

For example, a company may produce thousands of different components ofvarying shapes and sizes, many of which require a cover or wrap forpurposes of insulation and protection against heat and corrosion. Inorder to provide such covers or wraps for these various components usingcompression molding or vacuum molding, it would be necessary to providea mold for each section of covering to be applied to the thousands ofcorresponding components to be wrapped or covered. Thus, the presentinvention is directed to a product and process that may be used to applythese wraps or covers to components of any size and shape, without thenecessity of providing individual molds for each different size orshape.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a heat curable, circularor warp knitted fabric includes reinforcing and meltable resin fibersthat can be cured to form a more rigid material form. In one embodiment,the fabric includes a core spun yarn, wherein the core may be made fromglass, carbon, basalt, aramid or metal. The wrap surrounding the coremay include resin type fibers such as Poly(p-phenylene sulfide) PPS(sold under the trade name Ryton), Polyetherimide (PEI) sold under thetrade name Ultem, Polyether ether ketone (PEEK), Polysulfone (PES),Polyphthalamide (PPA), nylon, polyester, or polypropylene. Reinforcingfibers can additionally be added to the wrap. The fabric may containfrom about 10% to 100% of the core spun yarn.

In use, the core spun yarn is knitted into a circular or warp knitfabric, which may optionally include reinforcing fibers. The circularknit fabric may then be heat molded into any desired shape to serve as aprotective covering for a mechanical or industrial component, or may becut and sewn into or onto custom parts and then cured on the part oritem.

DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

FIG. 1 is a perspective view of one embodiment of a protective cover inaccordance with the present invention, wherein a pipe is wrapped with aheat curable knit fabric cover formed at least partially from core spunyarn;

FIG. 2 is a cross-sectional view of one embodiment of the protectivecover shown in FIG. 1, wherein the protective cover is a fitted sleeveformed from a circular knit;

FIG. 3 is a cross-sectional view of one embodiment of a protectivecover, wherein the protective cover has been cut and sewn and thenfitted onto a pipe, and wherein the seam is shown on an underside of theprotective cover; and

FIG. 4 is a cross-sectional view of one embodiment of a core spun yarn,having a core yarn made from multiple fibers and a meltable wrap, alsomade from multiple fibers, wherein the wrap is disposed about the coreyarn.

DETAILED DESCRIPTION OF THE INVENTION

The present invention includes, in a first embodiment, a heat curable,knitted fabric 10 containing yarn with a meltable resin outer layer, aswell as optional reinforcing fibers, which can be cured to produce amore rigid material form that can be used to serve as a protective wrapor cover 14 for various types of mechanical or industrial components, orother similar applications. In one embodiment, the fabric 10 includes acore spun yarn 12. Typically, core spun yarn is a yarn consisting of aninner core yarn 16 surrounded by staple fibers. A core spun yarn 12combines the strength and/or elongation of the core thread 16 and thecharacteristics of the staple fibers which form the outer surface, orthe “wrap” 18, as shown in FIG. 4. In the present case, the core spunyarn includes a core 16 preferably made from fibers of glass, carbon,basalt, aramid or metal. The meltable wrap 18 surrounding the core mayinclude one or more of resin type fibers such as Poly(p-phenylenesulfide) PPS (sold under the trade name Ryton), Polyetherimide (PEI)sold under the trade name Ultem, Polyether ether ketone (PEEK),Polysulfone (PES), Polyphthalamide (PPA), nylon, polyester, orpolypropylene. The meltable wrap may contain more than one type of resinfiber and may also include reinforcing fibers. In a preferredembodiment, the meltable wrap 18 is made from material having a meltingpoint of at least about 250° F., and preferably at least about 400° F.Reinforcing fibers can additionally be added to the textile compositefabric together with the core spun yarn 12, wherein the reinforcingfibers include but are not limited to glass, carbon, aramid, or metal.The fabric 10 may contain from about 10% to 100% of the core spun yarn12, depending on the desired properties and function of the finalproduct, and the rest of the fabric 10 may comprise reinforcing fibersor yarns.

After the core spun yarns 12 (and optionally, the reinforcing fibers)have been formed into a knit composite textile material (preferablycircular or warp knit), the composite textile fabric 10 may be cut andsewn into a preformed article and then positioned on or around acomponent or item, as shown in FIGS. 1 and 3, wherein the textilematerial is disposed about a pipe in the form of a cover 14. Then, heatmay be applied to the covered component, so that the meltable wrap 18 ofthe core spun yarn 12 melts (wholly or partially) and then the fabric 10rehardens into the desired shape around the component. It is preferableto provide a core spun yarn 12 having a meltable wrap 18 made frommaterial that has a melting point higher than the operating temperatureof the component, so that the wrap 18 does not melt during operation oruse of the component. Thus, the core spun yarn 12 may be specificallyengineered for specific components or purposes, based on the estimatedoperating temperature of the covered component.

In an alternate embodiment, the yarn may be knitted into a tape or slitinto a tape, wrapped around an item and cured as above.

In another alternate embodiment, the fabric 10 may be formed of acircular knit sleeve that is manufactured to specific specifications, sothat the sleeve fits around a component, such as a pipe 22, as shown inFIGS. 1 and 2. It may be advantageous to provide clamps 20 (or othersecuring means), as shown in FIG. 1, in order to securely hold the cover14 onto the pipe or other component.

Alternatively, after the core spun yarns 12 (and optionally, thereinforcing fibers) have been formed into a circular knit compositefabric 10, the composite fabric 10 may be placed into a mold and heateduntil the wrap 18 around the core 16 of the core spun yarn 12 hasmelted, in whole or in part. Then, when the composite fabric 10 isallowed to cool, the meltable wrap 18 hardens, so that the compositefabric 10 retains the shape of the mold.

It is contemplated that multiple layers of the composite fabric 10material may be used together. In one embodiment, the core spun yarns 12of the first layer are made from the same material as the second layer,which may include core spun yarns 12 alone, or may further includereinforcing fibers. In a second embodiment of the multi-layer compositetextile, the core spun yarns 12 of the first layer may be formed ofdifferent material from the core spun yarns 12 of the second layer. Inthis way, the composite fabric 10 may be engineered to produce differentfeatures or characteristics, depending on the desired use thereof. Suchcharacteristics may include melting point of the wraps, strength of thematerial, desired thickness, improved abrasion resistance, reduced cost,and improved environmental stability.

In another embodiment, a single layer knit fabric 10 is formed, whereinthe yarns alternate between core spun yarn 12 and reinforcing yarn, suchas glass, carbon, aramid or metal. In another embodiment, athree-dimensional knit fabric 10 may be formed, wherein the outer layeris formed of 100% core spun yarn 12, and wherein the spacer material andthe inner layer is formed of 100% glass fibers. It should be understoodthat various types of knit constructions may be used, so long as thecore spun yarns 12 are used in the range of about 10% to 100% of thefabric 10, with reinforcing yarns being used for the remainder of thefabric 10.

This composite textile fabric 10 may be used in any application thatrequires a rigid, heat resistant, non-flammable cover 14, insulation orsleeve positioned around machine components having a specific shape.Application examples include exhaust insulation covers, pipe insulationcovers, machinery covers (such as covers for turbines), rigid firebarrier panels, gun barrel covers, engine component covers, and thelike.

Because this heat curable composite textile fabric 10 is engineered tobe used for a protective cover 14 over industrial and mechanicalcomponents, and the like, it need not be developed to exhibit highlevels of strength and/or rigidity. Instead, the concept is to provide atextile material that may be easily shaped and molded to fit over thesecomponents, and need only have enough rigidity to maintain its shapeduring use. Thus, using a knit construction (which allows the textile tobe formed from thicker and bulkier yarns, but does not maximizestrength) is preferable to a weave, which requires less bulky yarns, andmaximizes strength and rigidity. Thus, it is contemplated that thecomposite textile fabric 10 may be formed by utilizing various knitconstructions, including but not limited to circular knits, warp knits,multi-layer fabrics and three-dimensional fabrics with spacer materials.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. Therefore, the spirit and scope of the appended claims shouldnot be limited to the description of the preferred versions containedherein. All features disclosed in this specification may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

What is claimed is:
 1. An insulated exhaust component, the componentcomprising: a hollow tubular member; an insulating sleeve positionedaround at least a portion of the hollow tubular member, wherein thesleeve comprises: a first sleeve portion comprising sleeve reinforcingfibers; and a second sleeve portion comprising a core spun yarn made, atleast in part, from a heat curable material; wherein the insulatingsleeve is configured to form a rigid, heat resistant, and non-flammablecover for at least the portion of the hollow tubular member when thesleeve is heated to a predetermined temperature.
 2. The insulatedexhaust component set forth in claim 1, wherein the sleeve reinforcingfibers are made from at least one selected from the group consisting ofglass, carbon, basalt, aramid and metal.
 3. The insulated exhaustcomponent set forth in claim 1, wherein the heat curable materialcomprises at least one selected from the group consisting ofPoly(p-phenylene sulfide), Polyetherimide, Polyether ether ketone,Polysulfone, Polyphthalamide, nylon, polyester and polypropylene.
 4. Theinsulated exhaust component set forth in claim 1, wherein the core spunyarn comprises an inner core yarn surrounded by a wrap including theheat curable material.
 5. The insulated exhaust component set forth inclaim 1, further comprising a second layer of a core spun yarn formedinto a circular knit structure, wherein the second layer is connected toand overlays a first layer of the insulating sleeve.
 6. The insulatedexhaust component set forth in claim 1, wherein the core spun yarncomprises between about 10% and about 99% of the cover.
 7. The insulatedexhaust component set forth in claim 1, wherein the insulating sleevecomprises a knit structure selected from the group consisting ofcircular knit, warp knit, multi-layer knit and a three-dimensional knit.8. The insulated exhaust component set forth in claim 1, wherein theinsulated exhaust component has a predetermined operating temperatureand wherein a melting point of the heat curable material is higher thanthe operating temperature of the insulated exhaust component.
 9. Theinsulated exhaust component set forth in claim 1, wherein the heatcurable material has a melting point of at least 250° F.
 10. A method ofmanufacturing an insulated exhaust component, the method comprising thesteps of: providing a hollow tubular member; forming a rigid, heatresistant, and non-flammable cover positioned around at least a portionof the hollow tubular member, wherein forming the cover furthercomprises: providing an insulating sleeve positioned around at least aportion of the hollow tubular member, wherein the sleeve comprises afirst sleeve portion comprising sleeve reinforcing fibers; and a secondsleeve portion comprising a core spun yarn made, at least in part, froma heat curable material; cutting the insulating sleeve into a desiredshape; wrapping and covering at least the portion of the hollow tubularmember with the insulating sleeve; heating the hollow tubular memberwrapped in the insulating sleeve to a predetermined temperature; andallowing the hollow tubular member and the insulating sleeve to cool, sothat the insulating sleeve hardens maintains its shape about the hollowtubular member to form the rigid, heat resistant, and non-flammablecover.
 11. The method set forth in claim 10, further comprising sewingedges of the insulating sleeve together.
 12. The method set forth inclaim 10, wherein the sleeve reinforcing fibers are made from at leastone selected from the group consisting of glass, carbon, basalt, aramidand metal.
 13. The method set forth in claim 10, wherein the heatcurable material comprises at least one selected from the groupconsisting of Poly(p-phenylene sulfide), Polyetherimide, Polyether etherketone, Polysulfone, Polyphthalamide, nylon, polyester andpolypropylene.
 14. The method set forth in claim 10, wherein multiplelayers of the insulating sleeves are used to wrap and cover the hollowtubular member.
 15. The method set forth in claim 10, wherein theinsulated exhaust component has a predetermined operating temperatureand wherein the melting point of the heat curable material is higherthan the operating temperature of the insulated exhaust component.
 16. Amethod of manufacturing an insulated exhaust component, said methodcomprising the steps of: providing a hollow tubular member; forming arigid, heat resistant, and non-flammable cover positioned around atleast a portion of the hollow tubular member, wherein forming the coverfurther comprises: providing an insulating textile positioned around atleast a portion of the hollow tubular member, wherein the textilecomprises a first sleeve portion comprising sleeve reinforcing fibers;and a second sleeve portion comprising a core spun yarn made, at leastin part, from a heat curable material; cutting the insulating textileinto a desired shape; placing the insulating textile into a mold;heating the insulating textile to a predetermined temperature; allowingthe insulating textile to cool, so that the insulating textile hardensmaintains its shape about the mold to form an insulating sleeve; andattaching said molded insulating sleeve to the hollow tubular member toform the rigid, heat resistant, and non-flammable cover.
 17. The methodset forth in claim 16, wherein the sleeve reinforcing fibers are madefrom at least one material selected from the group consisting of glass,carbon, basalt, aramid and metal.
 18. The method set forth in claim 16,wherein said heat curable material comprises at least one selected fromthe group consisting of Poly(p-phenylene sulfide), Polyetherimide,Polyether ether ketone, Polysulfone, Polyphthalamide, nylon, polyesterand polypropylene.
 19. The method set forth in claim 16, wherein theheat curable material has a melting point of at least 250° F.
 20. Themethod set forth in claim 16, further comprising placing at least oneadditional layer of the insulating textile into said mold, and attachingsaid multi-layer protective composite insulating textile to said hollowtubular member.
 21. The method set forth in claim 16, wherein theinsulated exhaust component has a predetermined operating temperatureand wherein the melting point of the heat curable material is higherthan the operating temperature of the insulated exhaust component.